Metal ion secondary batteries that have solid electrolyte layers using flame-retardant solid electrolytes (for example, lithium-ion secondary batteries and the like. Hereinafter they may be referred to as “all-solid-state batteries”) have such merits that systems for securing safety are easy to be simplified.
As to arts relating to lithium-ion secondary batteries, for example, Patent Literature 1 discloses a collector for a nonaqueous solvent secondary battery that includes: a first metal layer; and a second metal layer laminated on the first metal layer; in the collector for a nonaqueous solvent secondary battery, Vickers hardness (HV1, HV2) of each metal that constitutes the first and the second metal layers respectively and the thickness (T1, T2) of each of the first metal layer and the second metal layer satisfy HV1>HV2 and T1<T2, and the combination of the first metal and the second metal is any one of: (first metal, second metal)=(iron, aluminum), (titanium, aluminum), (stainless steel, aluminum), (nickel, copper), (iron, copper), (titanium, copper) and (stainless steel, copper). Patent Literature 2 discloses an electrode body for an all-solid secondary battery that includes a collector and a thin film type active material layer formed on the collector; in the electrode body, Vickers hardness of the collector is lower than that of the active material layer, and is in a range of 400 to 600. Patent Literature 3 discloses a negative electrode for a lithium-ion secondary battery that includes a current collector and a negative electrode active material layer formed on at least one face of the current collector; in the negative electrode, the negative electrode active material layer contains a negative electrode active material capable of storing/releasing lithium ions, and a stress relaxing material. Patent Literature 4 discloses a collector for a lithium-ion secondary battery negative electrode that includes a zinc layer, a copper layer and an indium rust preventive layer which are provided on at least one surface of an aluminum foil in this order.